Abstract

Many farms in the counties in the south of Sweden have difficulties with diseases spread by ticks; mainly babesiosis and tick-borne fever (TBF) but there are indications that borreliosis ought to be included. All of the tick-borne diseases radically decrease farm profit if the herd is affected. The production of the vaccine used against babesiosis since the 1920´s, will be discontinued in the near future and in addition to economical reasons it is therefore important to learn more about the diseases above.

During the summer and fall of 2002 and 2003, a farm in the island of Gotland was burdened with unusually many cases of bovine babesiosis. In total 43 animals fell ill and one died. The farm had not had any cases for over ten years; they do not vaccinate their calves but try to infect them naturally on tickinfested pastures. Bloodsamples from the cows showed that they were all negative for Borrelia burgdorferi sensu lato while most of the animals tested for Anaplasma phagocytophilum were positive. The most probable cause for the large outbreak of babesiosis is that the animals do not produce enough protective antibodies against Babesia eventhough they graze areas which are supposed to contain the disease, in combination with a simultaneos TBF-infection, which impairs the immunesystem.